Reciprocating piston pump or motor with annularly disposed parallel multiple cylinders



April 6, 1954 E. c. DUDLEY RECIPROCATING PISTON PUMP OR MOTOR WITH ANNULARLY DISPOSED PARALLEL MULTIPLE CYLINDERS 5 Sheets-Sheet 1 Filed Nov. 1, 1948 INVENTOR. 15 29144490 C DuoLsx April 6, 1954 E c DUDLEY 2,674,197

RECIPROCATING PIs'ro'N P'UMP 0R MOTOR WITH ANNULARLY DISPOSED PARALLEL MULTIPLE CYLINDERS Filed Nov. 1, 1948 5 Sheets-Sheet 2 l l l mmvron.

"Elan A20 C. DUDLEx BY g :0 firrorvsvs.

E. c. DUDLEY 74,197 RECIPROCATING PISTON PUMP OR MOTOR WITH ANNULARLY April 6, 1954 DISPOSED PARALLEL MULTIPLE CYLINDERS Filed Nov. 1, 1948 v 5 Sheets-Sheet 3 e a a b L M? 5233 \m 4 a M m 8 m m I. w Mm; Ww a M 2 1 wa m i p y a 4 V 0 e 5 m H 8 W O 8 D 2 .w 7 a. F 6

w a 42mm flrr NEYS.

April 6, 195 E. c. DUDLEY RECIPROCATING PISTON PUMP OR MOTOR WITH ANNULARL DISPOSED PARALLEL MULTIPLE CYLINDERS Filed NOV. 1, 1948 5 Sheets-Sheet 4 .a Q I W M WM 0 v M 8 m a W w w L L L V m. w a W 7 INVENTOR. .EbW-QQD C D0015);

9 IQTTOENE vs E. C. DUDLEY April 6, 1954 RECIPROCATING PISTON PUMP OR MOTOR WITH ANNULARL DISPOSED PARALLEL MULTIPLE CYLINDERS Filed Nov. 1, 1948 5 Sheets-Sheet 5 juuseuosr Pouvr OF Woes: Pmrs I N VEN TOR. C .0004 5g Val. vs KEYWAY 0 3 m 3 w T 0 3 #4 B m. m M WW 0 R mm EE M .I\ aw l/IGH POINT OF EccE/vnelc A 17- RNEYS.

HYoPAuL/c Moro/2 Patented .Apr. 6, 1954 UNl TED PATENT OFFICE I i REoIPnooArmGiPisToN" panama 1WITH"ANNULA1RLY DISPOSED PARALLEL MULTIPLE CYLINDERS Edward CiDudley Los Anieles,Calif; ass ignor ,to Eastman Pacific Company, Los Angeles,

Calif}, a corporation of California Application No vember 1, 194 8;'Serial"No. 5.73704 I 17 Claims. 1

' The present invention -relat'es to hydraulic mechanisms, and more particularly to a-hydraulic' mechanism which can be used either' as a pump or" as a hydraulic motor.

The present invention" may be applied-to -the" same general class of mechanisms as that set forth inmyPatentNo. 2,248,449 issued July- 8,.

1-941, although it is n'ot -necessarily limited there,- to.

' The -need for uses' fcr high pressure hydraulic mechanisms ior pumps: and motors has increased greatly in recentyears- Lighter units withhigher' operating i pressures, and smooth; quiet operat-- ing characteristics have been desired by engineers in many fields for designing: a wide variety'of product's. Among such products may be named; aircraft landinggear "retractors; wing flap c'on-- trols, tractor implement contr'ols'and-r truck hoisting mechanisms While the mechanism of: my above-mentioned patentworks satisfactorily up: to I quite high pressures; and" may be designed 'for,

use with hydraulic liquids having a wid range of visc-o'sities, nevertheless itha limitations which it is one object of the present' invention to over-- come.

Another object of the invention'istmmakan:

improved pressure hydraulic mechanism;

Another object is to malrean improved hydraulic mechanism wherein pressures *on working' areas of the mechanism'will' be compensated for by substantially equal and oppositely disposed forces.

"Another object is to make a hydraulic mechanism in which a working clearances will be oom trolled '-bythe viscosity- 0f liquid' fiowingthrough" r the mechanism.

Another object 'i's m-makea hydraulic 'mechae-r .Q 2 subjected toconstantly varyingv pressures on. different-portions' of: both sides thereof.

- These" and other objects and advantages invention, which will appear later herein, are attained, in accordance with one feature of themventiom by pistons-mounted toreciprccate in a plurality of parallel cylinders symmetrically arranged around the axis of ashaft having awobble plate mountedtherecn at'an acute angle'an-d ec- =centrica1ly thereto; so'ias toreciprocate thepis portsin one end of each of thecylinders, and having apertured valve openings: therein arrangedinpredetermined relation to the wobble plateythe valve disc having 5 a :pluralityof openings therethrough arranged to communicate with aplural ity of recesses on an area facing the valve-disc'- gitudinally of the shaft "under -pressures transmitt'edsto-opposite sides thereofautcmatically to vary the clearances from the'valvedisc inaccordancewiththe requirements ofliquids having different viscositiesflowing through the mechanism.

These and other features of the invention will be fully set forth 'inthe followingdescription and the accompanying drawings; wherein:

Fig. 1- is'a longitudinal sectional view-through a hydraulic mechanism embodying the present invent-ion;

Fig. 2 is *a'sectional view'taken in the plane of the line 2 4- of F'ig; 1;:

Fig. 3 is a sectional view taken in thez-plane of the line"=3--3- of "Fig. 1;

Fig. i is-a sectional view-taken inthe-plane of. the? line 4 4 of Fi .'=1';'

Fig. 5 -isa fragmentary sectional view-through a l rotatable: valve, taken in the plane of i the line 5*'=5 of- Fig: 1;

Fig; is a-wsect'ional view taken'in the "offset planes of.-'the"broken line 6- 5 of Figwl;

Fig. "his a-iragmentarysectional view' in the plane of-the'line 'l -l of Fig 1; showing the pump shaft and-wobble plate and' 'an' "end" portion of the 1 cylinder-f block I Fig. S de/ a longitudinal sctiofial view through an em dinient"-'bf-a modified ornf-o the inven ticnxteken on the ofiset liiie tt -t" m nis-r10; the

the

3 shaft and associated parts being rotated 180 from the position shown in Fig. 1;

Fig. 9 is a sectional view taken in the plane of the line 3-9 of Fig. 8;

Fig. 10 is a sectional view taken in the plane of the line ill-40 of Fig. 8;

Fig. 11 is a fragmentary longitudinal sectional view showing a modified pressure balancing and clearance controlling end plate structure of a mechanism otherwise similar to that shown in Fig. 8;

Fig. 12 is a fragmentary sectional view similar to Fig. 11, but showing a further modified end plate structure;

Fig. 13 is a sectional view taken in the plane of the line l3l3 of Fig. 12;

Fig. 14 is a sectional view taken in the plane of the line 14-14 of Fig. 12;

Fig. 15 is a diagrammatic view of a pump valve disc mounted over the cylinder ports similarly to Fig. 3 but in a different rotative position, and showing the angular relations of the various parts of one form of the invention when used as a hydraulic pump;

Fig.16 is 'a diagram similar to Fig. 15 but showing the device arranged for use as a hydraulic motor;

r Fig. 17 is an end elevational view of a main shaft taken from the left end thereof in Fig. 1, but with the shaft in a different angular position, showing the relative positions of a shaft axis and an eccentric shaft portion, a valve keyway, and a pair of hub keyways being shown in their relative angular positions; and

' Fig. 18 is a transverse sectional view through an eccentric shaft portion, showing the outline of an axially tilted hub mounted thereon, the

shaft having a wide keyway which permits a 3 the device it is desired to point out that all forms of the invention are capable of being used either as a hydraulic pump or as a hydraulic motor.

Where the term pump is used, it will be interpreted when practicable, through the specification and claims, to mean pump or motor.

Referring to the drawings, and considering first the structure shown in Figs. 1 to 7, inclusive, the device will be described first in its use as a high pressure hydraulic pump which is one of its important uses.

Referring to the drawings, Figs. 1 to 7 inclusive, a cylinder block 20 may be of metal, and preferably is of-steel, alloyed for toughness. It may be cast, forged or machined from bar stock. An axial bore 2| is machined through the cylinder block,'and a friction reducing bearing sleeve 22 is mounted therein, rotatably to support a shaft 23 therein.

A plurality of cylinders 24, here illustrated as five, see Fig. 6, are machined in the cylinder block with their axes parallel to that of the shaft bore 2|, andare preferably disposed symmetrically about it. The left-hand end of each cylinder, as shown in Fig. 1, which will be termed herein the outer end of the cylinder, opens into a cylinder port 25 in the cylinder block, see Fig. 6. The cylinder ports are in open communication with a valve chamber 27, which is also shown as formed in the cylinder block, see Figs. 3 and 4. The terms inward and outward as used throughout the present description designate toward, or away from, respectively, the inner or mounting end of the illustrated forms of the in- 4 venticn, which is the right-hand end as shown in Figs. 1 and 8. This limitation does not however extend to the terminology of the claims, since the invention obviously is capable of various types of mountings.

Aplurality of pistons, 28 are mounted, one in each cylinder, to have a close sliding fit therein. These pistons are cup-shaped, and have wide angle cone-shaped heads 29. In establishing the clearance between the pistons and cylinder walls it should be borne in mind that the pistons will tend to expand under extremely high pressure. A coil spring 30 may be mounted in each piston, to be held in compression between the piston head and the outer end of the cylinder. No such springs are required when the device is intended for use only as a motor, since the pistons then will be forced inwardly by the pressure of the propelling liquid, as will be understood from a reading of the present description.

A piston actuating wobble plate 3| preferably is mounted on an axially tilted hub 33, as best shown in Fig. '7, which in turn is mounted on an eccentric portion 36 of the shaft 23 to embody the invention cf my Patent 2,248,449 referred to previously herein. The annular plate 3! comprises a flanged disc, which is fitted onto the outer race of a ball bearing 32 of the thrust type. The inner race of the ball bearing 32 is fitted onto the axially tilted bearing support portion 33 of hub 33 which is disposed with the axis of said bearing support portion at an acute angle to that of the shaft 23 to which it is sccured by a key 38.

' The plane of the outer or left-hand face 31' of the wobble plate 31 which engages the ends of the pistons for actuation thereof is normal to the tilted axis of the bearing support portion 33" of the hub 33. of the shaft 23 upon which the hub 33 is mounted is eccentric to the shaft axis by an amount equal to, as set forth in my above-mentioned patent, the radial distance between the piston center circle defined by the axis of pistons 28 and the midpoint of a chord of such circle whose length is that of the piston stroke.

The action of the tilted hub mounted on the eccentric shaft portion causes the tilted axis of the wobble plate to precess in a generally conical path, with the exception'of the circular precession of the hub itself caused by its eccentric mounting on the shaft. The high point of the eccentric is located approximately in advance of the point of maximum inward or outward piston movement caused by the wobble plate as will be brought out later herein. This eccentric mounting of the wobble plate prevents radial sliding movement of the wobble plate across the piston heads during a high pressure stroke of the'piston, thus greatly reducing wear of the area of contact between the wobble plate and the conical piston heads.

The inner end of the shaft 23 is mounted in a ball thrust bearing 34, which in turn is mounted in a domed closure cap 35. The cap is secured to the cylinder block as by cap screws 3?. The inner end of the shaft projects inwardly beyond the closure cap for connection to a suitable driving or driven mechanism of a usual type.

A flange 39 on the shaft transmits the piston thrust on the shaft to the cap through the ball thrust bearing 34. A shaft seal 40 is mounted between the shaft 23v and the cap 35, and when the device isused as a pump with center intake, is arranged-to. prevent leakage of air into the The eccentric portion 36 anagram 5: ?v pump zbetweem the shaft and the cap; .since.=.with. the -.pump...irr operation :in this. .manner pressure.

withinthe capzis reduced below atmospheric, as.

tate herewith, asbya. key. 56. engaging. keyways' 55;-.a n 55? ipinjthe. shaft and valve-disc. respectively, 1A; key;..anchoring.pin 5.6! is. mounted in h keyway; 55;.':'. n.the valvedisc. 42.as.sho.wn in 3, A and. 5: to. prevent! the key: from: working; outwardly toward; anzend. .closure plate ;43.' The valve isyfil ted accurately between the .ported pla 3.; is;. secured in. place ,by. cap screws .44 to proyide, a housing including. the. cylinder block onbody portion Zllandthe-closure plate 43. All fits.between,the. orted. valve chamber face 21' of thecylinder block, thesides of the valve disc-42, and end plate 43, are ground. to .close tolerances so asto, provide suitable sealing. engagement of the valve disc with opposite sides. of: the valve chamber. Ira gasket is. desired .to seal the joint betweenthecylinder. block andthe end plate. its thickness must beconsidered in: designating. dimensions. For eXa-mp1e...with. hydraulic fluids having a viscosityrange; from 150 to .250 Saybolt sec..-at. 100= Grand. intended to operate thetemperature range from to 200 F. the total clearance for; both sides of; the. valve disc maybe from ;.O0075" to .0015". The amount of clearance of. course is adesign. factor and will vary with size,,vo lume,. pressure and other factors.

The valve disc 42 has a pair of arcuate portopenings-flandAS therethrough disposed to register with. successive cylinderport openings 25 upon rotatio n of: the shaft23. "The valve port 41 isgthe intakefor the purpose of the present description, andthe port .48 isthe outlet. Grooves 49 and; 50 are provided forlubricatin areasof thevalve faces radially. beyond the ports. From theinlet port ll apassage isnotched out of the outeror left-hand side 0f the valve radially inwardly, fromthe inlet port41, to-communicate withan inlet opening 52:111. the endclosure'plate 43. The inlet openin --52. is threaded toreceive aiusual; liquid supply pipefor supplying hydraulic liquid .to the pump. The shaft 23 terminates short of the end-plate 43 to providean inlet passage through the central bore of valve 42 to the passage 5| and thence to the valve inlet port' l'l.

.The outlet port 48-of the valve communicates through radially outward openings 48' in the valve, With=an annular-outlet chamber 53 surrounding the valve. This annular outlet chamberis provided by asubstantial lateral clearance between the periphery of the valve and the valve chamber side wall. A threaded, outlet opening 54 from the outlet chamber is threadedto receive a usual outlet pipe. A pair of. small relief holes 51 and 58 are provided one slightly beyond each end of. the valve outlet port 48 to communicate betweenthe cylinders and the opposite side of the valve disc during delayed opening. of theoutletport ,as will be brought'out later herein.

v In order to balance-the pressures onopposite,

sides of. the valve disc 42a pluralityof pressure balancing;recesses-59 are provided in theend closure plate ..43. facingsaidva-lve disc. These recesses areequal insizeandishape. to..the cy1inend; 21' 1 of 1 the ,valve chamber. 21, 1 and the uterendclosureplate. .43. The end-closure der ports-s: 2-15 and arellocated"oppositerthem, ,sosa: that .whenever one of; thervalvepports, llvor: 48;;012. openingsz. 51;- or. 58;..is: communicatiom.with..: a;-. cylinder ;port:.25,; it also:communicates zawith a.

recess 59 ofaequaharearThus, whatever; pressures;

positiveonnegatiw; thezinner; face; of; the.: valve. is.:subjectedi to from the cylinder...-ports,.;equal and. opposite'pressures;are; transmitted; by liquid; pressure, through .the. valveports: M andiflgand the; smaller openings; 51. and 5.8; by -.means:.;of Ethe recesses; 59:..to, theopposite faceof .the valve idiscs. This :simple parrangement, .byxtendingrto. balance;

thev constantly varyingpressures; from; the: cylindersiduringoperation .ongboth sidesof the valve disc, ,greatly:-yreduces valve. wear. It also '.-in.-- creases thepressure capacity ofthe: pumpibyueducing; valve; friction,. to :a minimum. even. ataexa. tremely; high; pressures, for; example. four: thou-'- sand;pounds;to;.the squareinch outlet pressure.-

Asgpreviouslycstated;in. the. form of the inven tion shown. in. Figs. 1 to; 7::inclusive, the maximum and minimum viscositiesof; the liquid.to-beusedl must be, considered establishingthe clearances between. the. faces of; the valyepdisc. and the valve chamber. Since the viscosity of the oils on otherhydraulic fluids .changesvggreatly with :variations in temperaturaand sinceit .is notialvvays possible r; -pr ti a 1e.: to retain then-hydraulic. fluid: with-- in reasonably narrow temperature.- ranges the .emciency -of..themechanism; shown imf igs; i to '7 will vary when the viscosity of the liquid passes beyond design limits in either direction.

Figs. 8 to 10 inclusive.showzawmodified formiof This modification;-rgivesihighly efficient operation with liquids having: a. wide the invention.

range or. viscosities. .Thispembodimentalso will be. described first-as .a; pump,:..althoug-h itxissalso capableof use asagmotor asswill bezbrought out later herein;

,The. entire :mechanismmf {Fig.1 8 to. theiright-nof the plane of the section-dine l-El,:l0:is..the:same

asthat shown in F. 1;1. Theseapreviously describedparts therefore will bedesignatedaby the: same reference numerals. as,in,Eig...1. Sincethey: operate-in asimilar. -rhanner,qtheir functions iWill' be understood, from a reading, ofgtheioregoing deer scription thereof.

as .will. beibro lght out 1ater.:-herein, itrmay com prisetheoutlet.

- An .-annular;recess. 63zis provided inwthe inner face of the1- .closure L plate 565,. and the housing means. definin the valvevchamber 22 1'.- includes-- a. .,pressure control plate. x or backin plate 64 mounted .in the recess. 63 with a .-:.substantial amount of;v lateral clearance asshown eat? 63 fibe tween its periphery and the side .wall .:of.ithe ;re-

ocess toprovide open communic ationibetweenzthe nular ;outlet :cham-ber'53; and the: rearzface off the pressurecontrol plate-.64. The. inner end-face of..plate;-64-formsthe outer-,side of:-.valve2cham.-1 ber 21 and is adapted to bear more or. less-closely:v against.theouter faceof. valve; clisc;42.='yvhose.;ine.-

ner face,..as' before, .bears against-theendfaoe l lfi of the'oylinder block .at'thesinnel side of. the valve chamber; and'the combined axial length of mem;

bers 42 and 64 issomewhat less,than-the.axia1 distance between'theouter end face of'recess 63 and the ported cylinder block end face 21' so as to provide a space 65 between the outer face of the pressure control plate and the closure plate 60, which comprises in effect a hydraulic chamber for urgin the pressure control plate toward the valve disc to maintain suitable sealing engagement of the inner and outer faces of valve disc 42 with the opposite sides of the valve chamber 21. The pressure control plate 64 has an outward tubular flanged extension 65 thereon which fits slidably into the inner end of the inlet opening 62, and is sealed therein by a hydraulic O-ring 61. This permits limited axial movement of the "pressure control plate in its recess toward and away from the outer face of the valve disc 42.

The pressure control plate 64 has pressure balancing recesses 58 in the inner face thereof in a manner similar in shape, size and position to the recesses 59 in the fixed end closure plate 43 of Fig. 1. From each of the pressure balancing recesses 68, two small holes 59 and 10 extend through the pressure control plate 64. Each of these holes opens into a separate cylindrical recess H in the outer face of the pressure control plate 64.

The bottom of the recess 63 in the end closure plate 60 also has a plurality of cylindrical recesses 12 therein, similar, and similarly located, to those in the pressure control plate 54. A corresponding plurality of small floating sealing sleeves 13 are provided, each mounted with one of its ends in a recess ll in the pressure control plate 64, and its other end in the corresponding recess 12 in the end closure plate Bil. Hydraulic rings 14 and 15 seal the ends of each sleeve '13 in its respective recesses. These sleeves act simply as sealing devices, to seal off the inner ends of recesses H from the space 66 at th outer end of the pressure control plate, and to expose these inner ends to th pressure from the pressure balancing recesses 68.

As will be brought out in a description of the operation of the device later herein, there i at least one of the openings through the valve disc 42 in open communication with each cylinder port 25 throughout substantially the entire cycle of rotation of the valve. Therefore the pressure of each cylinder, at its cylinder port 25, will be transmitted through one of the valve ports 41 or 48 or one of the small holes and 58, which is in registry with the cylinder port, to the pressure balancing recess 68 which is opposite that particular cylinder port, and thence through the hole 69 and in the pressure control plate leading from the pressure balancing recess to the inner ends of the two corresponding cylindrical recesses H in the pressure control plate 64. This latter pressure in the recesses H urges the pressure control plate 64 toward the valve disc with a rotatively varying pressure similar to that of the pressure balancing recesses 68. The amount of the forec exerted by this pressure will be'controlled of course by the design of the area of the cylinders 1 l The overall effective area of the heads of the cylindrical recesses 1|, preferably is equal to the maximum effective pressure areas on the inner face of the pressure control plate which they are intended to balance. These areas are those under pressure, through the liquid film on the face of the valve, from the outlet port in the valve, and from th outlet chamber 53 around the valve disc.

It is clear that a relatively negative pressure will exist in the intake port 41 of the valve and in each of the cylinder ports 25 durin an intake stroke of its piston when the device is operating as a pump. But regardless of whether the pressure at the cylinder port is positive or negative it will be balanced on the valve disc and on the pressure control plate 64 during the entire rotative movement of the device.

In addition to this constantly varying compensating pressure, an overall pressure is maintained on the exposed rear area of the pressure control plate 64 by the open communication between the annular outlet chamber 53 and the space 66 at the outer face of the plate 64, through the clearance space 63'. Any tendency for the clearance between the valve disc and the pressure plate 54 to increase beyond an efiective sealing condition would permit oil to flow across the face of the valve disc and thus would decrease the pressure on the inner face of the pressure control plate 64.

This would cause the pressure control plate to be moved inwardly by the hydraulic pressure on its outer face. However, since a greater pressure is required to maintain a predetermined clearance between the faces of the valve disc and its opposed chamber faces, with a more viscous than with a less viscous fluid, the amount of clearance at these points will vary automatically with changes in viscosity of the fluid.

With this construction of Figs. 8 to 10 inclusive, it is preferred to fit the valve disc on the shaft 23 with a close sliding fit, so that the valve disc can center itself between the two opposed faces between which it operates and thus will tend to adjust the clearances on both faces of the valve in accordance with varying pressures and viscosities which may exist during operation.

In order to assure seating of the pressure control plate 64 against the valve disc 42 under relatively low outlet pressure conditions, I have shown compression springs Ti extending through central bores in the sleeves 13 and hearing at their ends against the plate 64 and the end plate 50 7, so as to exert a moderate inward thrust resiliently urging the plate 64 against the valve disc. Under ordinary operating conditions, however, the compression springs H are not necessary. With these springs omitted, and using liquids of medium to heavy viscosities, usually within onehalf revolution or less of the shaft 23 the outlet pressure against the outer face of the pressure control plate, will seat the pressure control plate against the valve disc, thereby placing the device in operative condition.

In the further modified form of the invention shown in Fig. 11 the same general type of recessed pressure balancing plate and sealing sleeves therefor are employed as shown in Figs. 8 to 10 inclusive. The same reference numerals. therefore which were employed in connection with Figs. 8 to 10, inclusive, will be employed in connection with Fig. 11, adding thereto the suffix a. This latter modified form of the invention is designed to permit operation by reversing the relative positions of the inlet and outlet ports. When the direction of shaft rotation is reversed, for example, from that of Figs. 8 to 10 inclusive, the central opening 62a in the end closure plate 6911, which was the inlet 6| in the form shown in Fig. 8, now will be the outlet.

In this embodiment of Fig. 11, a hydraulic O ring 18 seals the periphery of a pressure control or balancing plate 64a to the wall of its recess 63a in the end closure plate 60a. A pair of ball check valvesifls andti8llr..arei mounted in the ends of a coilzcompression spring 8| and are urged thereby toward opposite .endszof avalve recess 82. The outerv ball checkr8il is seated in the end of a passage 83 which communicates with the opening 62a in the outer end-closure plate 60a (now the outlet, previouslyin Fig. 8 ridescribed as the inlet opening). ,The inner ball-checkfle is seated in the end ofa passage 84 which-communicates with: the annularainlet chamber-"55a (previously described as the outletchamber). A lateral passage85 communicates. from the valve recess 82 with; the space 66a at :the. exposed rear or outer face of the pressure controlplate 64a. Thus, regardless of; whether .thetannular chamber 53a, or the opening 62a is .:under the greater pressure, the higher pressure will be transmitted to the outer face of the pressure control plate 64a, and thelow'pressure side will be sealed off from this area .by its ballcheck valve.

Another modified form of the invention isillustrated in Figs. 12;. 13 and 14. This modification comprises a pressure. balancing-plate assembly which is shown as mounted on the :end of a cylinder block and valve assembly similar ,tofithat shown in Figs. 1 and 8. 1 The modification shown in Figs. 12 to 14, inclusive, is limited as tothe maximum pressure which it is capable of developing. In this mannen'it. comprises, in effect,

- its own safety valve.

In this latteriformof thewinvention an an" nular intermediate spacing memberfil is vprovided between an end closure plate. 9! and. the

body orcylinder-block' 2i! OflthedGVifiGy These parts are held in assembled relation onthe (El/111L- der block 20 by capscrews 92. The annular spacing memberllfl' has. an :inner bore-portionsfi of reduced diameter, and an enlarged outer --bore portion 94, with an offset shoulder SS-between the two bore portions. A pressure control plate 91"is mounted for limited axial movement-in the oilset bore of the intermediate spacingmember 90, and is sealed peripherallyin the reduced bore portion 93 thereof by a hydraulic' oring 98. .The

pressure control plate" 8! is mounted to EPI'OVldfl the desired working clearanceonboth sides of the valve disc. The pressure :control plate '91 has a plurality of pressure balancing: recessesi'99. in

inwardly toward the -shoulderi95. Sincezthe outer face of the pressure control platalllisvsealed by the O ring 98:from the higher. pressure of'the "annular outlet chambera 53, and is .open'monly to the lower pressure-of an inlet opening "E82 in the end closure plate at, the springs we provide the only stabilized pressure urging thepressure control plate '91 inwardly toward the valve disc. This spring pressure maybe compared to that supplied in the modificationoffFigs- 8' to 10 inclusive by the outlet pressure applied to the exposed area of the outer face of the plate 54.

A rotative varying pressure balancingiarrangement somewhatsimilarto that *provided by the sleeves 'lS and cylinders H in the embodiment shown in Figs. 8 to 10 is provided fonbalancing thepressures imposed by the actions of the pistons '28 in'cylinders 24. upon operation of1the device.

' From 7 each of the pressure-balancing.srecesses:

- :99. :in the .inner face of. the; pressure control plate 91, a hole I03 communicates with-a cylindrical rrecess 104 in the outer face of thepressure'control plate .91. These cylindricalrecesses each qhavea top-area other than thatof the hole. I03, :equalr substantially. to the,.pressurized areas of :thevalve discto be balanced as vpreviouslyde- -=scribed inv connection-withathei embodiment ilwlustrated in Figs; 8. to 10, inclusive. sealing In this modified construction of Figs. 12 to 14,

::inclusi-ve,=.the springs loll urge the pressure con- ..trol plate 91 inwardly into operative position :against the valvedisc (i2 -to resist, the pressures -::which tend tojmove the'plate- 9'! away from the valve;disc.

Additionallythe plugs [556881 the cylinders 04 and 7 thereby causethe f pressure :.-;transmitted through the liquid from each of the cylinders; 24 withwhich the pressurebalancing recesses-99 are in-communication, to be trans- ;umitted-through the holes lll3v to the inner ends of the cylindrical recessescllll. This-transmits rotatively balancing .forces substantially, equal and opposite to those imposed by the constantly varying 'fillid, pressures: from; eachgof the cylin- 1 ders. 24.

"With. this latter i-modification, of the device,

whenitheoutlet or higher pressure: exerts a sepxarating force-between the .valve'faces and their opposed valve chamber surfaces which, exceeds the contraryforce-exerted on the-pressure control plate by the springs Hill, the pressure control plate 91-.will beforced outwardly away from the valve disc 42, and'permit ,excessfluid to bypass between the valve inlet and outlet ports 41 and 48. Thus the pump will not generate pressures .exceeding that; determined by the total pressure of the'springs- I00. "This is avaluable asset under; some operating conditionswherein the pump: contains its own limitation as to the maximum pressure which may be-generatedby it. At pressures below this -maximum cutout pressure, theplate 91- willbe moved outward slightly todevelop a proper operating clearance by liquids having a higher viscosity in thesame manner as described for the form shown in Figs. 8 to lflyinclusive.

Up tosthis point in the-present description; the

1 various forms of the invention have-beemder scribed'only in theiruse as'pumps. "I'hiswas done to facilitate an understanding of-thefunctions of the various mechanisms and the hydraulic operations involved.

j be borne in mind; first, that in order for the wear compensating feature of my previously designated former. Patent 2,248,9149 topperate the offset. of the high point of the eccentric portion 36.. of the shaft, 23-must be approximately ,of shaft rotationahead of piston movement at the initiationof a powernstroke, and, second,

--that what-hasbeen termed the outlet :port-(48 of the valve disc) shouldpreferably/register with each piston port on its high pressure stroke. ,-As a. pump the outward stroke; ofthe pistonvwill be the power or higher pressure strokegwhilesas a 7 motor the inward stroke is the higher pressure p or power stroke.

One method of accomplishing the wear compensating adjustment for either direction of rotation, either as a pump or as a motor, is by providing alternately usable keyways 45 and 48 for the eccentric hub 35 (see Fig. 17).

These keyways are arranged so that with the hub keyed to the proper keyway, the intake and exhaust valve ports will open respectively into each cylinder port 25, 12 of shaft rotation after the piston in that cylinder has started on its high and low pressure strokes, respectively, as illustrated in the diagrams of Figs. 15 and 16. Also by proyiding for substantial reversal of the operative position of the eccentrically mounted hub 33, the

parts can be arranged so that the relative position of the high point of the eccentric shaft portion 36 will be approximately 90 ahead of the point of contact of each piston with the wobble plate at the beginning of the power stroke of that piston. By this arrangement the wear compensating feature of my prior Patent 2,248,449 can be made to occur on the high pressure stroke regardless of whether the device is used as a pump or a motor, or is rotating in one direction or the other. 7

In order more easily to visualize the operation of the device, a brief description will be given of two operative arrangements of the invention, one as a pump and one as a hydraulic motor, both having the same direction of rotation. From J of the shaft 23, while the two keyways 45 and 45 in theeccentric portion 36 of the shaft 23 are each onset 6 from a diameter of the eccentrio portion of the shaft. The reason for this will be brought out in the following description of operation.

' In Fig. 15, which illustrates the device set up for operation as a pump with counterclockwise rotation as viewed from its outer end, the valve disc 42 is shown in its position at the beginning of a power or outward stroke of the piston mounted in the cylinder beyond the cylinder port 25a. In this position, the valve keyway 55,

as shown in Fig. 17, would be diametrically opposite a point midway between the ends of the valve outlet orhigh pressure opening 48 and the valve inlet or low pressure opening 41. In

the indicated structure this would be 31 ahead or a line H0 marking the leading edge of the valve outlet opening 48. However, in the position of the parts illustrated in Fig. 15, this line H0 is 12 back of the edge of the cylinder port 25a, the position of which is indicated by a line H I. At this point, the small opening 51 is just opening into the cylinder port 25a.

The pistons in the cylinders opening into the cylinder ports are centered relative y to the angular length of the cylinder ports. Therefore, in order for the innermost point of the wobb e plate to be centered on the piston in the cylinder opening into the port 25a, in Fig. 15, the innermost point of the wobble plate must be 25 ahead of the line Ill since, as indicated by lines I and H2 the angular length of each of the cy ports is 50.

If the wobbl plate hub keyways and 48 were diametrically in line with the valve keyway 55, the innermost point of the wobble plate would be diametrically opposite the valve keyway and thus would be only 31 ahead of the line I I!) since that would be the mid-point of the 62 angle between the adjacent ends of the valve disc intake and outlet ports 41 and 48. This then would bring the innermost point of the wobble plate only 19 ahead of the line i H at which the piston should initiate its stroke. It is for this reason that the 6 oiiset of the hub keyways 45 and 46, shown in Fig. 17, is provided so as to move the position of the wobble plate relatively 6 ahead and thus to bring it at the midpoint of each piston at the desired initial position of its power stroke.

The power stroke continues through an angle of shaft rotation of 180. The pressure generated in the cylinder during this first 12 of the power stroke before the valve opens is equalized on opposite sides of the valve disc through the small opening 51 which communicates with the pressure balancing recess facing the opposite side of the valve.

This first 12 of rotation gives the cylinder an opportunity to build up pressure approximately to match that in the annular outlet chamber 53. This reduces surging and makes for smooth operation. The outlet valve port 48 opens into cylinder port 25a after this 12 of travel and remains in communication therewith through the 118 of its length, plus the length of the cylinder port. This makes a total of 180, so that the outlet valve port 48 closes with respect to cylinder port vDuring this 12 of initial travel on th intake stroke, the cylinder port 25a is in communication with the pressure balancing recess facing the opposite side of the valve disc through the second small opening 58. The intake valve port similarly remains open throughout the 118 of its length plus 50 of cylinder port length and closes at the completion of the 180 intake stroke.

This completes the 360 cycle.

For operation as a pump, the hub 33 is keyed to the eccentric 36 so that the high point or maximum eccentricity of the eccentric portion 35 of the shaft 23, is, as indicated in Fig. 15, approximately ahead of the innermost point of the wobble plate. In the arrangement shown in Fig. 16, where the device is to be operated as a hydraulic motor, the hub 33 is keyed to the other keyway 46 on the eccentric shaft portion 36. This brings the high point or maximum eccentricity of the eccentric shaft portion 36 approximately 90 ahead of the outermost point of the wobble plate.

Since, when the device is used as a hydraulic motor, the inward stroke of the piston as illustrated in Fig. 1 is the power stroke, the high pressure (previously out et) valve opening 48 now is positioned to open into the cylinder port 25a, at the initiation of an inward stroke of the piston. This is brought about by the reversal of the positio'n of- 'the wobble plate. f the wobble-platein this arrangement, due to the 6 offset'of the -keyway 46, is positioned directl-yin -line*with'the center of the piston in the-pump inletopening -62.

The outermost point the cylinder opening-into the cylinder port 25a. 'With these-exceptions, the cycle follows substantially the same coursedescribed above for Fig. 15,

but with the further exception that "the 12 por- -tion=of 'each'strokewhen the valve is closed is device-will be frequent, if desired, the metal of the-shaft between the-two keyways 45 and 4t may-beremoved, as shown at H4 in Fig. 18,

- so that the key 38 then isfree to swing from one end to the-other of this widened keyway.

Uponreversal of direction of the'shaft 23, the hub 33 will rotate relativelyto the shaft until the-key 38 abutsagainst the other end of the widened keyway. With this arrangement, no

reseating of the key for reverse rotation would be necessary and the previously described readjustment for reversalwould be automatic.

This feature is particularly useful "in conjunction withthe-embodimentshown in Fig. 11.

In the embodiment of Figs. 8 to 10, inclusive,

it'would not befeasibleto operate the device either as a-pump or a motor with the higher pressure applied to what has been described as In such case the higher pressure could not reach the rear face of the pressure control plate 6 1, which, 'as'previouslyset forth, is necessary in this embodiment forsuccessful operation'of the device.

Inthe embodiment-illustrated in Fig. 11, .it

" would be feasible to-operate the device as a pump or hydraulic motor with the higher pressure applied to the inlet "opening 62a, since, as "pre viously brought out, the'ball checks "I9 and 80 act to apply the higher pressure to the rear face of the pressure control plate 64a regardless of which opening is used as the high pressure side.- In the embodiment shown :in Figs. 12 to 14,

' inclusive, it also'would not be feasible to apply the higher pressure to'the central opening in the end plate 9|.

While I have illustrated and described a pre-' ferrediform of my'invention, and some .modifications thereof, it'will be apparent to those familiar with :the art that the device is capable of several additional modifications without departing fromthe spirit "of the invention: Itis desired, therefore; not to limitthe invention except'assetforth inthe following claims.

I claim:

- ports in cyclical-succession," said ihousing means 1. A hydraulic'mechanismcomprisinghousing means having a plurality of parallel cylinders therein arranged symmetrically arounda central shaft bore in said housing means, a piston mounted *to reciprocate in each cylinder, said housingmeansdefining a valve chamber adjacent one end of said-cylinders and substantially concentric with the shaft bore, and also de fining a port at said one end of "each cylinder in communication with one end of said-valve chamber, a shaft rotatably mounted in said bore, a rotary valve mounted on said'shaft to rotate therewith in said valve chamber and to overlie said ports, one side face of said valve seating against said one .end of the valvechamber, said valve. having intake. and .outlet ports therein adapted alternately to register with said cylinder including a plate mounted tohaveseating'engagement with the opposite side face of said valve from that seated against said one end of thevalve chamber, said plate having a plurality ofrecesses'therein adapted to communicate with the cylinder ports, said recesses being of similar sizeand shape, and disposed endwise oppositely to said cylinder ports, and drive means operatively interconnecting said shaft and said pistons to rotate said valve and to reciprocally move said pistons synchronously with the rotation of said shaft.

"2. A hydraulic mechanism comprising housing means having a plurality of parallel cylinders therein arranged symmetrically around a central shaft bore in said housing means, a piston mounted to reciprocate in'each cylinder, said housing means defining a valve chamber adjacent one end of said cylinders and substantially concentric with the shaft bore, and also defining a port at said one end of each cylinder in communication with one end of said valve chamber, a shaft rotatably mounted in said bore, a

rotary valve mounted on said shaft to rotate therewith in said valve chamber'and to overlie said ports, one side face-of said valve seating against said one end of the valve chamber, said valve having intake and outlet ports therein adapted alternately to register with said cylinder ports in cyclical succession,-said housing means including a backing platemounted in said valve chamber to have resilient seating engagement with'the opposite side face of said valve from that seated against said one end of th'evalve chamber, said backing plate having a plurality of recesses therein adapted to communicate with the cylinder ports through the valve intake and outlet ports, said recesses being of similar size and "shape, and'disposed endwise oppositely to said cylinder ports, and-drive means operatively interconnecting said shaft and said'pistons to rotate said valve and to reciprocally move said pistons synchronously with the rotation of said shaft.

3. A hydraulic'mechanism comprising housing means having a plurality 'of parallel cylinders therein arranged symmetrically around a central shaft bore in said'housing means, a piston mounted to reciprocate in each cylinder, said housingimeans'defining a valve chamber ad- 'jacent one end of said cylinders and substantially .chamber,.a shaft rotatably mounted in said bore,

a rotary valve mounted on said shaft to be free for limited slidable movement thereon, and mounted to rotate therewith'in said "valve chamber and to overlie said ports, the inner side face of said valve seating against said inner end of the valve chamber, said valve having intake and outlet ports therein adapted alternately to register with said cylinderv ports in cyclical succession, said housing means including a pressure control plate at the outer end'of the valve chamber movable toward and away from the valve and having its inner side in seating engagement with the outer side face of the valve, hy-

draulic pressure -control means operatively connected to transmit pressure from the cylinders 1 pistonsto' rotate said valve and i'eciproca-lly -to 15 move said pistons synchronously with the rotation of said shaft.

4. A hydraulic mechanism comprising housing means defining a cylinder, a piston mounted to reciprocate therein, a shaft rotatably mounted adjacent said cylinder, said housing means also defining a valve chamber and a port in a side thereof opening into said cylinder, said housing means including a pressure control plate mounted on the other side of said chamber from said port, and movable toward and away from said ported side, said shaft extending into said valve chamber, a valve mounted on said shaft to rotate therewith, said valve being disposed in said valve chamber between said ported side and said pressure control plate, said valve having a high pressure port and a low pressure port therein, and a passage communicating from the high pressure valve port to the face of said pressure control plate outwardly from said valve to urge the pressure control plate toward sealing engagement with the valve disc.

5. A hydraulic mechanism comprising housing means defining a cylinder, a piston mounted to reciprocate therein, a shaft rotatably mounted adjacent said cylinder, said housing means also defining a valve chamber and a port in a side thereof opening into said cylinder, said housing means including a pressur control plate mounted on the other side of said chamber from said port, and movable toward and away from said ported side, an area of said pressure control plate at the side thereof away from the valve chamber comprising a portion of a hydraulic chamber, said shaft extending into said valve chamber, a valve mounted on said shaft to rotate therewith, and free for limited adjusting movement axially thereof, said valve being disposed in said valve chamber between said ported side and said pressure control plate, said valve having a, high pressure port and a low pressure port therein, said pressure control plate having an opening therein adapted to communicate between the valve high pressure port and said area of the pressure control plate to urge the pressure control plate toadjacent said cylinder, said housing means also defining a valve chamber having a port in a side thereof opening into said cylinder, said housing means including a pressure control plate mounted on the other side of said chamber from said port,

and movable toward and away from said ported side, said shaft extending into said valve chamher, a valve mounted on said shaft to rotate therewith, said valve being disposed in said valve chamber between said ported side and said pressure control plate, the valve chamber being of greater diametrical width than the valve or the pressure control plate to provide a marginal area in open communication with the face of the pressure control plate outwardly from the valve, said valve having a high pressur port and a low pressure port therein, and a passage communicating from the high pressure valve port to said open marginal area.

'7. A hydraulic machine comprising housing means defining a cylinder, piston mounted to reciprocate in the cylinder, said housing means also defining a valve chamber having opposite sides thereof substantially flat and a port in one of said fiat sides in communication with the cylinder, the opposite flat side having a recess corresponding in area and extent to the port; a valve mounted for rotation parallel to and between the opposite sides of the valve chamber to have sealing engagement therewith, said valve having an opening therein adapted to communicate between the port and the recess, and means for coordinating movements of the valve with those of the piston.

8. A hydraulic machine comprising housing means defining a cylinder, 2, piston mounted to reciprocate in the cylinder, said housing means also defining a valve chamber having opposite sides thereof substantially flat and a port in one of said flat sides in communication with the cylinder, the opposite flat side having a recess corresponding in area and extent to the port, a valve mounted for rotation parallel to and between the opposite sides of the valve chamber to have sealing engagement therewith, said valve having an intake port and an exhaust port therein adapted to communicate alternately between the cylinder port and the recess, and means for coordinating movements of the valve with those of the piston.

9. A hydraulic machine comprising housing means defining a cylinder, a piston mounted to reciprocate in the cylinder, said housing means also defining a valve chamber having opposite sides thereof substantiall flat and a port in one of said fiat sides in communication with the cylinder, the opposite fiat side having a recess corresponding in area and extent to the port, a. valve mounted for rotation parallel to and between the opposite sides of the valve chamber to have sealing engagement therewith, said valve having an intake port and an exhaust port therein adapted to communicate alternately between the cylinder port and the recess, the valve ports being spaced apart an angular distance greater than the angular extent of the cylinder port, the valve having an opening therein sealed from said valve ports and located in the angular area between the valve ports, said opening being adapted to communicate between the cylinder and the recess, and means for coordinating movements of the valve with those of the piston.

10. A hydraulic machine comprising housing means defining a cylinder, a piston mounted to reciprocate in the cylinder, said housing means also defining a valve chamber and a cylinder port opening therefrom into the cylinder, a valve rotatably mounted in the valve chamber, said valve having intake and, exhaust ports therein adapted to register with the cylinder port, said housing means including a valve support element engaging the side of said valve opposite to said cylinder opening, said valve support element having a pressure balancing recess therein of approximately the same area and extent as the cylinder port, and means for coordinating movement of the valve and piston.

11. A hydraulic machine comprising housing means defining a cylinder, 2, piston mounted to reciprocate in the cylinder, said housing means also defining a valve chamber and a cylinder port opening therefrom into the cylinder, a, valve rotatably mounted in the valve chamber over said cylinder port, said valve having intake and exhaust port therein adapted to register with the cylinder port, and a valve support element adapted to conform closely to the side of the valve opposite to that over the cylinder port, said valve support element having a pressure balancing recess therein facing the valve of approximately the size and shape of the cylinder port, said recess being in communication with the cylinder port, and means for coordinating movement of the valve and piston.

12. A hydraulic machine comprising housing means defining a cylinder, a piston mounted for reciprocation therein, said housing means also defining a valve chamber and a port in an end thereof opening into said cylinder, a recess in an opposite end of said valve chamber from said port, a valve rotatably mounted in said valve chamber and having oppositely disposed faces thereof in sealing engagement with said ported end and with said recessed end of said valve chamber, said valve having intake and exhaust ports therein adapted to register with the cylinder port and having an opening therein adapted to communicate between the cylinder port and the recess to transmit balancing pressures from the cylinder to opposite faces of the valve, and means for coordinating movement of the valve and piston.

13. A hydraulic machine comprising housing means defining a cylinder, a piston mounted for reciprocation therein, said housing means also defining a valve chamber and a port in an end thereof opening into said cylinder, said housing means including a pressure control plate mounted at the opposite end of said valve chamber from said port, a valve rotatably mounted in said valve chamber and having sealing engagement with said ported end of said valve chamber and with said pressure control plate and having intake and exhaust ports therein adapted to register with the cylinder port, said pressure control plate having a pressure balancing recess in the side thereof in sealing relation with the valve, said valve having an opening therein adapted to communicate between the cylinder port and the recess to transmit balancing pressures from the cylinder to opposite sides of the valve, means acting on said pressure control plate to urge it toward sealing relation with the valve, and means for coordinating movement of the valve and piston.

14. A hydraulic machine comprising housing means defining a cylinder, a piston mounted for reciprocation therein, said housing means also defining a valve chamber and a port in an end thereof opening into said cylinder, said housing means including a pressure control plate mounted at the opposite end of said valve chamber from said port, a valve rotatably mounted in said valve chamber and having sealing engagement with said ported end of said valve chamber and with said pressure control plate and having intake and exhaust ports therein adapted to register with the 15. The arrangement set forth in claim 14, the margin of the pressure control plate being sealed from the opening in the valve, and a spring acting on said pressure control plate and urging it toward the valve.

16. A hydraulic machine comprising: housing means defining a plurality of parallel cylinders, a valve chamber adjacent the forward ends of said cylinders, and a plurality of cylinder ports communicating between said valve chamber and the forward ends of the respective cylinders; a piston mounted for reciprocation in each of said cylinders; a drive shaft mounted for rotation and having its axis parallel to the cylinders, said shaft extending within the valve chamber; said cylinders and pistons being disposed at angularly spaced positions about the axis of the shaft, and the longitudinal axes of the pistons defining a piston center circle about said shaft axis; a valve mounted on said shaft within said valve chamber and having an intake port and an exhaust port angularly spaced from each other and positioned to register with the cylinder ports; a wobble plate mounted about said shaft rearwardly of said pistons and having a forward face engaging the pistons at their rearward ends, said wobble plate having an axis normal to said forward face and inclined at a predetermined angle relative to the shaft axis to control reciprocation of the pistons between a rearward position engaging the rearmost portion of said forward face and a forward position engaging the foremost portion of said forward face; means mounting the wobble plate on said shaft so that said inclined axis of the wobble plate at said forward face is offset radially from the shaft axis at an angular position spaced approximately from that of said rearmost portion of the forward face of the wobble plate; the amount of such offset being equal to the radial distance between said piston center circle and a chord of such circle, the length of said chord being equal to the stroke of said pistons between said rearward and forward positions; and means for reversing the angular position of said rearmost portion of th wobble plate, relative to the position of said offset, about the shaft axis.

17. A hydraulic machine as set forth in claim 16, in which said last named means comprises a key engaging a keyway of sufficient angular extent to permit a partial relative rotative movement between the position of said offset and the position of said rearmost portion of the wobble plate upon reversal of the direction of rotation of the shaft.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 436,567 Reynolds Sept. 16, 1890 2,373,723 Wahlmark Apr. 17, 1945 2,392,980 Fawkes Jan. 15, 1946 2,397,314 Grosser Mar. 26, 1946 

